Virginia Weather: 7/29/15

Last evening, there was the threat of rain, but I don’t think it actually rained.

This morning has been warm, humid and totally overcast.

The visible satellite imagery shows the cloud cover over the state. Most of the clouds are stratoform, but there are some taller, embedded cumulus clouds present.

The infrared satellite imagery shows that none of the embedded cumuloform clouds have any depth to them as of yet.

The most prominent feature in the water vapor satellite imagery is the low pressure system over northwestern Ontario. Notice the moisture being pulled cyclonically into this system. For Virginia, there is plenty of moisture present along the plume being drawn into this system.

The 12Z upper air sounding from Washington, DC, shows that there is plenty of moisture in the Mid Atlantic today. The surface dewpoint is 69 F and there is 1.75 inches of precipitable water present.
There was 15 J/kg of Convective Available Potential Energy (CAPE), and that has likely increased through throughout the morning.

The shear is very low, with only 4 kts of deep-layer shear present, and 9 kts of low-level shear present. This is why the rains have been so heavy- the storms are not moving very fast (or at all), so the storms hover in one spot and dump a lot of rain over an extended period of time.

The Storm Prediction Center (SPC) Mesoscale Analysis surface observation map shows that dewpoints have risen into the low 70s throughout most of the state. Winds are light and no major frontal boundaries are standing out.

The CAPE map shows that CAPE has increased to over 1000 J/kg just north of my location, and it also shows that there is little capping inversion present.

Overall, I think the increasing CAPE and ample moisture will produce more thunderstorms and showers throughout the state today. However, with the low shear, storms will be poorly ventilated and likely not reach severe limits. The low shear and low upper wind speeds will cause storms to move slowly, making the primary threat today flash flooding in low lying areas.

Thank you for reading my forecast.

The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The forecasted upper air soundings are from
The surface observation and upper level charts are from Unisys Weather.
The satellite data is from NASA – MSFC


About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
This entry was posted in Local WX, Practicing Concepts, Predictions, Satellite Imagery and tagged , , , , . Bookmark the permalink.

2 Responses to Virginia Weather: 7/29/15

  1. Joe Pennewell says:

    I like the write up, and I am inclined to agree with the the graphics and your comments. Looks like a good weekend here in the plains #Lawrence #Kswx thanks.


    • Glad you like my post! Most of the images come from SPC, but I try to explain what is happening.

      Also, I am learning, just like all forecasters, so if you have some feedback, I’d love to hear it!

      Thank you for commenting and reading my blog!


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